KEY POINTS:
Engineers are rushing to provide a rough cost estimate for lowering Auckland's Southwestern Motorway into a covered trench along Onehunga Bay.
The Government's Transport Agency expects a trench - which the Auckland Regional Council has suggested for restoring Onehunga's access to the waterfront - would add substantial cost to the $230 million Manukau Harbour motorway crossing duplication project.
That would include providing a slightly steeper climb from Onehunga to Hillsborough, and keeping the trench dry.
But agency acting regional manager Tommy Parker confirmed it was seeking initial cost estimates for a board meeting on Friday.
The agency is due then to consider a request by Auckland City, backed by Roskill MP Phil Goff, to shift the Onehunga motorway section west in conjunction with an ambitious 11ha foreshore reclamation and restoration plan costing $18 million to $30 million.
Mayor John Banks and city development committee chairman Peseta Sam Lotu-Iiga, who is National's candidate in the local Maungakiekie electorate, have proposed a three-way funding split between the city, the regional council and the agency. That would leave a 15m corridor on the landward side of the motorway, which is to be doubled to eight lanes, to lay a trenched railway line to Avondale and power cables without destroying recreational space around Onehunga Lagoon.
The Transport Agency, formed from Transit NZ and Land Transport NZ, has also offered to spend $10 million to build a pedestrian bridge across the motorway to the foreshore.
But the regional council wants it to consider lowering a kilometre of motorway, after chairman Mike Lee said anything less would leave "a sort of Berlin Wall between the community and foreshore".
Although the Auckland Volcanic Cones Society proposed a covered motorway trench along 500m of waterfront at project hearings more than a year ago, Mr Parker said the regional council's intervention "came out of the blue a little bit".
"We'll be getting some initial engineers' estimates - but there's only so much work we can do between now and the board meeting."
His agency, which began the harbour crossing duplication in April from the Mangere side, was hoping to move bulldozers to Onehunga in two weeks towards a self-imposed deadline of completing the project for the 2011 Rugby World Cup.
Mr Goff said he was happy for the trench to be considered as long as that did not cause delays, jeopardising getting the reserve and foreshore done.
"You can always at some point down the track deal with putting a trench under it - but I suspect that will significantly increase the cost."
He had an enduring desire to improve the bay, where his father swam before its beaches were destroyed by motorway construction in the 1970s.
The Onehunga Enhancement Society also fears chances of restoring the waterfront may slip away, although chairman Jim Jackson acknowledges a trench could ultimately be funded from selling Government property no longer needed along an inland rail corridor.
The Auckland Regional Transport Authority has decided a rail link to Avondale should follow the motorway instead, through a tunnel from Onehunga Bay to Hillsborough.
Although Mr Lee says reclaiming the harbour without lowering the motorway would be a "cosmetic job which is not good enough", he acknowledged to the Herald that a two-stage proposal might be acceptable - "as long as we actually sign up to the second stage".
Volcanic society member Richard Reid, a landscape designer who prepared extensive submissions on the crossing project, said Transit had had "five or six of years of planning to ... deliver an integrated solution, and now it's all piecemeal".
He and Maungakiekie Community Board chairwoman Bridget Graham said Onehunga was, as a key gateway to Auckland, no less deserving of an integrated solution to the central city where a covered motorway trench is planned through reclaimed land below Victoria Park.
Trench warfare:
Auckland City Council: Wants to restore Onehunga Bay alongside the Southwestern Motorway.
Auckland Regional Council: Says about 1km of motorway between the bay and Onehunga township should be lowered into a trench to avoid a "Berlin Wall" effect.
Transport Agency: Says the trench plan would substantially increase the cost of its $230 million Manukau Harbour motorway crossing duplication project.
